The uni-ball PWE Chalk Marker writes on and wipes off making it the perfect tool for sign writing on non-porous surfaces such as chalkboards. The Chalk Marker is rain-resistant – so your message will hold up outdoors – but the ink is water-based so if you want to remove it simply wipe away with a damp cloth, or a little mild detergent if stubborn. Perfect for pub, café and restaurant signs. 1.8 – 2.5mm bullet tip.